package java10;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.Properties;
//JDBC工具类
public class JDBCUtils {
    //只有静态的成员变量才能被静态代码块和静态方法访问
    private static String url;
    private static String user;
    private static String password;
    private static String driver;
    //使用静态代码块，读取一次文件，就拿到这些值
    static {
        //读取资源文件，获取值
        try {
            Properties pro = new Properties();
            //获取src路径下的文件的方式--->Classloader类加载器
            ClassLoader classLoader = JDBCUtils.class.getClassLoader();
            URL res = classLoader.getResource("jdbc.properties");
            String path = res.getPath();
            pro.load(new FileReader(path));
            url = pro.getProperty("url");
            user = pro.getProperty("user");
            password = pro.getProperty("password");
            driver = pro.getProperty("driver");
            Class.forName(driver);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    //获取连接
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url,user,password);
    }
    //释放资源
    public static void close(Statement stmt,Connection conn){
        if(stmt != null){
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if(conn != null){
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
    //释放资源（方法重载）
    public static void close(ResultSet rs,Statement stmt, Connection conn){
        if(rs != null){
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if(stmt != null){
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if(conn != null){
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
}
